Tire pressure indicator



Jan. 13, 1970 L E. KILMARX ET AL 7 3,489,167

TIRE PRESSURE INDICATOR Filed Oct. 5, 1967 v 2 Sheets-Sheet 1 INVENTOR.

LOUIS E. KILMARX BY RICHARD BR ATTORNEY.

Jan. 13, 1970 L. E. KILMARX ET AL 3,489,167

7 TIRE PRESSURE INDICATOR Filed 001:. 5, 1967 2 Sheets-Sheet 2INVENTORS. LOUIS E. KILMARX RICHA D E. BROWN ATTORNEY.

United States Patent 3,489,167 TIRE PRESSURE INDICATOR Louis EdwardKilmarx, Dickson, and Richard Edward Brown, Franklin, Tenn., assiguorsto Scovill Manufacturiug Company, Waterbury, Conn., a corporation ofConnecticut Filed Oct. 5, 1967, Ser. No. 673,072 Int. Cl. B60c 23/04,29/00; F16k 15/20 US. Cl. 137227 6 Claims ABSTRACT OF THE DISCLOSURE Atire pressure indicator which can be screwed onto the regular valve stemand provides a fill nipple. A biased diaphragm inside the indicatorflexes at low pressure to show petals through a window immediatelysurrounding the fill nipple.

This invention relates to a tire pressure indicator. More specifically,this invention relates to a tire pressure indicator which will give avisual signal when the air pressure in the tire falls below a certainpreset minimum pressure.

The prior art is replete with all sorts of pressure indicating devicesfor use with automobile tires. Most of these devices are complicated andhave been unreliable. The bulk of them require the removal of theindicator to fill or release air from the tire. They have been expensiveto manufacture.

The present invention relates to a tire pressure indicator adapted tofit onto the tire stem of a conventional tube or tubeless tire and tocommunicate with the air inside the tire. Additionally, the indicator isequipped with a fill nipple whereby the tire may be filled or air letout without removal of the indicator. The present indicator provides areliable and readily visible indicating signal and is of simple andinexpensive construction.

Other features of the invention will be apparent from the followingspecification wherein:

FIG. 1 shows an indicator embodying the invention adjacent the tirestern and rim of an automobile wheel;

FIG. 2 is an enlarged sectional view taken through the centerline of anindicator embodying the invention and in which the left-hand side of thesection shows the diaphragm as it would be connected to a tire havingsufficient air pressure, while the right-hand side of FIG. 2 shows thediaphragm as it would be disposed when the indicator is connected to atire having low tire pressure;

FIG. 3 is a sectional view taken on the line 33 of FIG. 2;

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 2;

FIG. 5 is an enlarged exploded view of an indicator embodying theinvention;

FIG. 6 is a greatly enlarged sectional view taken on a radial planethrough one side of the diaphragm; and

FIG. 7 is a greatly enlarged sectional view taken on a radial plane andshowing a portion of the valve seat in the fill nipple of an indicatorembodying the invention.

Referring more specifically to the drawings an indicator embodying theinvention is generally designated 10 in FIG. 1. It is shown aligned withthe tire stem S of a conventional tubeless tire having the rim R. Aportion of a wheel cover C which may be used in association with anindicator embodying the invention is also shown.

Referring now to FIG. 2, the indicator embodying the invention comprisesa housing having an upper end 12 and a lower end 14. In the embodimentshown the housing is, roughly, acorn-shape. More scientifically, thehousing has the shape of a surface of revolution about the axis of thehousing. The upper end of the housing terminates upwardly in a fillnipple 16 which is on the axis of the housing, is threaded and isadapted to receive a standard fill cap. Inside the nipple is a centralpassage 18 which narrows as at 20 and presents a downwardly dependingsharp annular shoulder or seat 22 (FIG. 7). Therebelow, the nipplepassage widens and is defined by an annular depending wall 26. The lowerend of the annular wall 26 is formed with radial slots 46 for reasonswhich will also appear.

A fill check valve 28 having an actuating stem 30 which protrudesupwardly in the passage 18 is also provided. Valve 28, which may be astandard valve core pin, has the annular central enlargement 32 which isengaged on its lower side by the axial spring 34 and is pressed upwardlyso that its upper surface seats on the sharp annular shoulder 22 of FIG.7. Above the annular enlargement 32 comprising the valve proper, theactuating stem 30 is stepped outward to form guide surfaces which directthe proper seating of the valve element. A central downward projection36 helps hold the axial spring 34 in proper position.

The upper end of the housing is made of a clear plastic such as Lexanand an annular window 40 provides a view into the annular indicatorchamber 42 which surrounds the depending wall 26. An elastomeric gasket44, of L-shape section, is secured about the periphery of the upper endas shown. This serves the dual purpose of providing a rattle-reducingcushion between the indicator 10 and the wheel disc or cover, and alsocauses a section of the clear plastic upper end 12 to benon-transparent. An annular depending flange 50 is formed on the upperend below the collar.

The lower end 14 has in its bottom wall a central upward recess with anopening 52 which is threaded to receive the threaded end of a valvestem. The opening is on the axis of the housing. The recess is taperedtoward the threaded opening as at 56 to accommodate the conventionaltire stem S and has an annular inward flange 58 which may sealinglyengage the rubber of the stem S.

Depending centrally from the opening 52 is a valvecore-pin-engagingprojection 60 adapted when the indicator 10 is mounted on a stem S todepress the conventional valve core or other valve already in the stemto hold it open. A plurality of holes 62 are disposed about theprojection 60 and communicate with the nipple passage 18. A centralupward point 64 positions the lower end of spring 34.

Disposed in the lower end 14 about the opening 52 is an annular well 66which is formed with drain openings 68 to permit the venting toatmosphere of the air below the diaphragm.

Inner and outer lands are provided on the upper surface of the lower endinside and outside of the Well. The lands are formed with annulargrooves as at 70 and 72.

An axial spring 74 is disposed in the well and rests on the bottomthereof. On the upper end of the spring is disposed a ring 76 which isformed with a shoulder 78 neatly engaging the spring. The ring extendsupward to end in a blunt edge 80 intermediate the inner and outer lands.The shoulder 78 may be extended outward in an annular flange which mayabut the underside of the diaphragm as in the right side of FIG. 2 toprovide upper stop means. This will prevent the cramping or jamming ofthe petals against the window 40.

The assembly is completed by a diaphragm which is annular in shape andhas on its inner and outer peripheries enlarged lips 91 and 92,respectively. These lips fit into the grooves 70 and 72, respectively.In assembly the upper end 12 is brought down on the lower end 14 withthe diaphragm 90 in between. The lower end of the wall 26 forces the lip91 into sealing engagement with the inner groove 70 and the outerportion of the upper end forces the outer lip 92 into sealing engagementwith its groove 72. Flange 50 is sealed to the upper periphery of thelower end 14.

Thus the indicator chamber 42 is defined by the upper end and thediaphragm 90. Access into the chamber from the nipple passage below thevalve enlargement 32 is through the slots 46 so that the air pressurewithin the tire communicates to the inside of the indicator chamber 42.

Referring more specifically to the configration of the diaphragm 90(FIG. 6) it will be noted that the diaphragm is molded in corrugatedshape and its central upper corrugation receives the edge 80 of the ring76. Immediately outward of the central corrugation of the diaphragmprojects upwardly an annular row of petals 96 integral with thediaphragm. As shown, the petals are separated from each other byV-shaped notches and are held erect half way up their heights bytriangular webs 98 also integral with the diaphragm. The petals areflexible and as shown in FIG. 2 when the diaphragm is up as under thelow tire pressure the petals are pressed against the inner surface ofthe window 40 showing their color through the window.

The shape of the petals together is actually a development of the innersurface of the transparent window 40, so that when the diaphragm is upas in the right side of FIG. 2, the petals, inclined inwardly, form acontinuous band at the windows.

When the diaphragm is in the down position as shown at the left side ofFIG. 2 as when the tire pressure is sufficiently high, the petals arehidden behind the gasket 44 and do not appear through the window 40. Tomake the contrast more striking in the appearance of the window asbetween low pressure and suflicient pressure, the outside surfaces ofthe petals 96 may be made, for instance, red in color while the insidesurfaces may be black.

It will be understood that the air pressure acting on the upper side ofthe diaphragm 90 is opposed by the pressure of the ring 76 engaging theunderside of the diaphragm. The ring is urged upwardly by the spring 74.The spring 74 and the ring 76 thus comprise biasing means. When the airpressure is suflicient, the spring will be overcome to the extent shownon the leftward side of FIG. 2 while when the air pressure is low, thespring will dominate the force acting on the upper surface of thediaphragm 90 to raise the diaphragm, petals and all, to the positionshown in the right-hand side of FIG. 2.

It should be understood that variations from the specific constructionshown are possible within the scope of the present invention. Forinstance, it should be understood that the indicator shown and describedis equally useful with tube-type tires. Further, it may be that thesnap-in type mount can be incorporated directly into the lower end ofthe indicator with no need for threaded connections, conventional valvestems, etc. Also, the indicator can be used with an extension, betweenitself and the tire valve, to accommodate the various desired lengths.

Moreover, the various parts may have any of a large number of shapes andconstructions and equivalents. For instance, the annular row of petalsmay be a continuous upstanding flange. Means may extend out into chamber42 from wall 26 to keep the petals or such flange against the window 40,or at least from collapsing into chamber 42. Such means may make thewebs 98 unnecessary. The biasing means shown, the spring 74 and ring 76may be replaced by gas pressure permanently sealed in the chamber orwell below the diaphragm. Therefore, the invention should be regarded ashaving the scope of the appended claims and equivalents thereof ratherthan the specific example above described.

What we claim is:

1. A compact tire pressure indicator adapted to be mounted on a wheeland connected to a tire and comprising a housing having a fill nipplewith a central passage at its upper end and at its lower end tireconnection means, a spring-pressed fill check valve disposed in thenipple passage, diaphragm means disposed across the housing and havingits outer periphery sealed about the housing, the diaphragm beingcentrally apertured and sealed about the aperture to the tire connectionmeans, the diaphragm defining with the upper end of the housing anindicator chamber, the upper end of the housing having an annular windowimmediately adjacent to and surrounding the fill nipple, said connectionmeans and the nipple passage below the valve communicating with thechamber, the lower end of the housing enclosing biasing means urging thediaphragm means against the air pressure in the chamber and toward thewindow so that part of the diaphragm means is visible immediatelyadjacent the fill nipple when the air pressure in the chamber is below apredetermined pressure.

2. A tire pressure indicator as described in claim 1 wherein the biasingmeans comprises a spring disposed in an annular well in the said otherend of the housing and surrounding the tire connection means.

3. A tire pressure indicator as described in claim 1 wherein the housinghas the shape of a surface of revolution with the tire connection meansand the fill nipple disposed on the axis.

4. A tire pressure indicator as described in claim 1 wherein the windowis inclined inwardly and upwardly toward the fill nipple and thediaphragm means has an annular row of upstanding petals which engageagainst the inside of the window when the air pressure in the chamber isbelow a predetermined pressure.

5. A tire pressure indicator as described in claim 4 wherein the biasingmeans comprises a pressure ring engaging the diaphragm at a lesserradius than said annular row of petals and on the opposite side of thediaphragm therefrom.

6. A compact tire pressure indicator adapted to be mounted on the end ofa tire stem and comprising an acorn-shaped housing having a fill nipplewith a central passage at its upper end and at its lower end a threadedstem-receiving opening, a spring-pressed fill check valve disposed inthe nipple passage, annular diaphragm means disposed across the housingand with the upper end of the housing defining an indicator chamber, theupper end of the housing having an annular window immediatelysurrounding the nipple, said opening communicating with the chamberthrough the central hole in the diaphragm, the nipple passage below thevalve also communicating with the chamber, the lower end of the housingenclosing biasing means concentric with the opening and urging thediaphragm against the air pressure in the chamber and toward the windowso that part of the diaphragm means is visible when the air pressure inthe chamber is below a predetermined pressure.

References Cited UNITED STATES PATENTS 2,704,045 3/1955 Biesing ll6343,022,795 2/1962 Abrams 137227 3,230,968 1/1966 Struby l37227 HAROLD W.WEAKLEY, Primary Examiner US. Cl. X.R.

